The present invention relates to a motive assembly for selectively controlling shedding of warp threads in a loom.
According to a general aspect of the present invention there is provided a motive assembly for moving a plurality of warp yarns in a loom between upper and lower shed positions, the motive assembly including a plurality of selectively controllable ultrasonic cyclic motors, each of which is drivingly connected to one or a group of said warp yarns for moving the warp yarn(s) between upper and lower shed positions.
Preferably the ultrasonic cyclic motor is a piezo motor, preferably operating at a frequency of between 20-40 KHz.
The motor may be drivingly connected to the warp yarn by a rigid elongate heald rod which is driven by the motor. The motor may directly contact the elongate heald rod in order to displace it longitudinally. Alternatively, the motor may drive the heald rod indirectly via a transmission means such as a drive gear or wheel.